Side force control devices

ABSTRACT

An airplane embodying devices functioning to provide an essentially true side force acting to alter the horizontal flight path of an airplane without sideslip and to avoid roll movements normally associated with maneuvers of this type.

United States Patent Wheldon 1 Aug. 7, 1973 SIDE FORCE CONTROL DEVICES[56] References Cited [75] Inventor: Wilbert G. Wheldon, Palos Verdes UD ST TES PATENTS Peninsula, Calif. I 7 2,597,020 5/1952 Nissen 244/76 73A N tli t' L A l i I I sslgnee Z? mp corpora OS nge es PrimaryExaminer-Milton Buchler Assistant Examiner-Stephen G. Kunin Flledi 1971Att0r neyHarold L. Fox and Willard M. Graham [211 App]. No.1 114,818

D [57] ABSTRACT Related Application am An air lane embod ing devicesfunctionin to rovide 63 C f S N 66 449 A 24 p y g p 1 I an essentiallytrue side force acting to alter the horizon- 19 tal flight path of anairplane without sideslip and to avoid roll movements normallyassociated with maneu- [52] US. Cl. 244/83 R, 244/75 R, 244/77 E, vetsof this yp 244/92, 318/586 [51] Int. Cl. B64c 13/04 2 Claims, 4 DrawingFigures [58] Field of Search 244/83 R, 83 C, 75 R,

244/76 R, 77 R, 77 A, 77 E, 87, 91, 92, 51;

PATENIEUMIK mxrm stantial rolling or sideslip.

SIDE FORCE CONTROL DEVICES This application constitutes acontinuation-in-part of copending patent application, Ser. No. 66,449,filed Aug. 24, 1970, entitled Direct Side Force Control Device. v

The present invention relates to control surfaces for airplanes and moreparticularly to cooperating control surfaces enabling the airplane tomake flat turns functioning to change the flight pathwithout sideslipand roll movements normally associated with changes of this type.

It is sometimes desirable in the control of aircraft to maintain thewings level position thereof at such time as it is effecting anazimuthal change in its flight path. This is especially important in thecontrol of military airplanes with a depressed reticle sight when makinga dive bombing run since this method of operation prevents thependulummotion of the optical sight when normal bank and turn steeringcorrections are made. This pendulum motion which degrades the pilotsability to track accurately is caused by the banked airplane attitudewhich problem is minimized by the invention described herein. I

Accordingly it is a principal object of the invention to provide anairplane incorporating controlled surfaces and control means wherebywings level stability of the airplane is maintained at such times as theflight path azimuth is altered without introducing any sub- Althoughthe-characteristic features of the present invention are particularlypointed out in the appended claims, the invention itself, and also themanner in which it may be carriedout, will be better understood byreferring to the following description taken in connection with theaccompanying drawings-forming a part of this application and in which:

FIG. 1 is a plan view of an airplane incorporating variable pitchpropellers cooperating'with the rudder of the plane representing amethod of providing the results as described herein. f

FIG. 2 is a plan view'of an airplane incorporating control surfacesacting as asymmetric drag producing devices and cooperating with therudder of the plane to provide the results described herein.

FIG. 3 is a plan view of the airplane incorporating control surfaceswhich produce side forces acting through or near the center of gravity(c.g.) of the plane to provide the results described herein.

FIG. 4 constitutes ablock diagram of the control de-.

vices cooperating with components described in FIG.

Referring to the drawings and particularly to FIG. 1, in this figure aplan view of an airplane 11 is shown including a fuselage, right andleft wings and tail empennage 12, 1'4, 16 and 17, respectively. Theplane 11 is propelled by a pair of variable pitch propellers l8 and 19.The empennage 17 includes a vertical member 21 having afixedrelation'with respect to the fuselage l2 and a conventional movablerudder member 22.'However the members 21 and 22'may be of unitaryconstruction, movable as a whole unit, and if so constructed arereferred to as an all-movable tail.

The airplane 11 also includes internal control components 23 joiningside force and yawing momentsurfaces in a manner to be described as thedisclosure progresses. FIG. 4 shows all of these control components.'Among them are a switch-24 which the pilot places in the on" positionwhen desiring to operate the aircraft in the side force control mode. Aposition transducer 80 measures the pilots inputs to the rudder pedalcontroller 26 signifying the direction which he wishes to turn theairplane. This controller 26 may alternatively be a twist-grip mountedat the top of the control stick or any other controller within thecockpit which may be provided as a pilot controller.

Lateral balance as used throughout the subject application refers to anairplane the wings of which remain in an unbanked attitude while theplane effects an azimuth change in its flight path, i.e.,"the change iseffected without rolling or sideslip being imparted to the airplane 11or the airplane 11 makes a flat turn.

For purposes of illustration it is assumed a dive bombing run is to bemade. Referring to FIG. 4, a block diagram showing components of theinternal control components is presented. Signals transmitted to therudder 22 and pitch-changing devices to the propellers l8 and 19originate with and are responsive to movements of the pilots rudderpedals indicated by the numeral 26 (FIG. 4), when switch 24 is on".These sig-. nals are transmitted to the devices controlling andamplifying the pitch control devices 28 and 29 which sigrects the signaltransmitted to the yaw damper actuator indicated by the numeral 32 whichin turn corrects the rudder position to null the sideslip angle.

During a dive bombing run elimination of rolling action of an airplanewill eliminate the pendulum effect of the depressed optical sight (notshown), thus tracking of a target will be rendered less difficult due tothis improvement. Also target lead time needed utilizing theconventional rudder and aileron bank and turn maneuver is minimized. Theflight means disclosed herein functions in a novel manner to eliminateor minimize these objections.

Referring again to FIG. 1, the forces acting on the airplane 11 will bebetter understood from the following explanatiomlt is assumed that theflight path of the airplane is to be altered to the left during thecourse of a bombing run. To effect this change'the switch 24 is firstmoved to its on position energizing the internal control components 23and operatively coupling the rudder pedals 26 to the present side forcecontrol system.

Then when the rudder pedals 26 are moved-by the pilot in the normal leftturn direction, the propeller pitch actuators 28 and 29 are operated toincrease the pitch of the right propeller l8 and decrease the pitch ofthe left propeller l9. v

The thrust of the right propeller 18 therefore increases .and the thrustof the left propeller therefore decreases, resulting in the total changein thrust on the airplane 11 remaining essentially zero, but producing aleft yaw movement. The sideslip sensor 31 in conjunction with the yawdamper 32 causes the-rudder to deflect to the right to cancel theunbalanced yawing movement due to propeller pitch change, i.e., yawingmoment due to propeller pitch change (F, -F,,)a now equals oppositeyawing moment due to rudder (F, )(b) thus leaving only the unbalancedside force due to rudder force F, to the left (FIG. 1). This unbalancedside force is now a radial accelerating force which causes the airplane11 to turn left essentially without banking. The moments M and M actingabout the center of gravity 36, due to rudder and differential propellerchange, respectively, being equal and opposite cancel each other, thelinear side force F can be transposed to the c.g. of the airplane 11leaving only the force 37 which is equal to the force F The force 37,acting through the c.g. of the airplane 11, along with the initial yawmotion caused by differential propeller thrust, results in a change inthe azimuth flight path causing the airplane 11 to turn to the left in aflat turn.

When the airplane ll assumes its desired new flight path the pilot easesoff on the side force controller 26 (rudder pedals in this example) asdesired to maintain proper tracking. Reference may be had to mycopending application Ser. No. 66,449, filed Aug. 24, 1970, for furtherdescription of such controller.

Referring to FIG. 2, the airplane 41 operates and functions similarly tothe airplane 11 of FIG. 1. In this embodiment the airplane 41 has hingedclam shell-like structures 42 and43 mounted at the aft end of the tiptanks 44 and 46. Othermechanisms near the wing tips which produceessentially pure drag will function in a similar fashion.

Inasmuch as the internal control components 47, connecting the clamshell-like structures 42 and 43, function substantially the same as thecontrol elements for the variable pitch propellers 18 and 19 of FIG. 1,a detailed discussion in this respect is not believed necessary.

Again it is assumed the airplane 41 is making a left turn during a divebombing run. The clam shell-like structure 43 ispartially open, asindicated by dotted construction in FIG. 2, and the rudder 49 is movedto the right as shown in dotted construction. Thus it will be seen thatthe rudder 49 will provide a true side force 51 functioning to effect anazimuthal change in its flight path without any substantial rolling orsideslip motion being imparted to the airplane 41.

Referring to FIG. 3, the airplane 61 shown in this figure operates andfunctions similarly to the airplane 11 of FIG. I. The airplane 61embodies pivotally mounted fences 62 and 63 which are rotated equallyclockwise or counter-clockwise about a point causing the side forces Fand F to pass through the center of gravity 36 of the airplane 61.

Utilizing forces created by the fences 62 and 63 functioning in themanner of the previous embodiments, has an advantage over theembodiments shown in FIGS. 1 and 2 in that a true side force is providedacting through the center of gravity of the airplane 61 without the useof the rudder 64.

I claim:

1. In an airplane having a pair of variable pitch propellers, a rudder,a pitch changing actuator for each of said propellers and a rudderactuator, the combination comprising: i

a. a pilots control member movable in either of two substantiallyopposite direction from a neutral position,

b. on-off switch means accessible to the pilot,

c. side force control means coupled to said pilots control memberthrough said on-off switch means, and

d. means connecting the output of said control means to said pitchchanging actuators and to said rudder actuator,

e. said side force control means responsive to movements of said pilot'scontrol member functioning to change the pitch of at least one of saidpropellers to produce yaw in one direction and to move said rudder inthe other direction to cancel the yaw moment of said propellers, wherebyaerodynamic forces are present providing a true side force acting at thecenter of gravity of said airplane insuring the latter will change itsazimuthal flight path without any substantial rolling or sideslip. I

2. In an airplane which includes a rudder and opposite wing mountedvariable-pitch propellers, apparatus operable to perform a flat turncomprising:

a. means interconnecting the control means for said rudder with thepitch control means for said propellers,

b. a manually-controlled switch operable to actuate said interconnectingmeans from an inoperable to an operable condition,

c. a pilots turn controller connected to said interconnecting means, and

d. side force control means in said interconnecting means responsive tosaid turn controller when said interconnecting means is operable todifferentially change the pitch of said propellers in one yawproducingdirection and to deflect said rudder in the opposite yaw-producingdirection,

e. whereby the lateral side force on said airplane from said rudderdeflection combined with an initial yawing motion started by saidpropeller pitch differential operation can produce an essentiallywings-level flat turn of said airplane.

1. In an airplane having a pair of variable pitch propellers, a rudder,a pitch changing actuator for each of said propellers and a rudderactuator, the combination comprising: a. a pilot''s control membermovable in either of two substantially opposite direction from a neutralposition, b. on-off switch means accessible to the pilot, c. side forcecontrol means coupled to said pilot''s control member through saidon-off switch means, and d. means connecting the output of said controlmeans to said pitch changing actuators and to said rudder actuator, e.said side force control means responsive to movements of said pilot''scontrol member functioning to change the pitch of at least one of saidpropellers to produce yaw in one direction and to move said rudder inthe other direction to cancel the yaw moment of said propellers, wherebyaerodynamic forces are present providing a true side force acting at thecenter of gravity of said airplane insuring the latter will change itsazimuthal flight path without any substantial rolling or sideslip.
 2. Inan airplane which includes a rudder and opposite wing mountedvariable-pitch propellers, apparatus operable to perform a flat turncomprising: a. means interconnecting the control means for saId rudderwith the pitch control means for said propellers, b. amanually-controlled switch operable to actuate said interconnectingmeans from an inoperable to an operable condition, c. a pilot''s turncontroller connected to said interconnecting means, and d. side forcecontrol means in said interconnecting means responsive to said turncontroller when said interconnecting means is operable to differentiallychange the pitch of said propellers in one yaw-producing direction andto deflect said rudder in the opposite yaw-producing direction, e.whereby the lateral side force on said airplane from said rudderdeflection combined with an initial yawing motion started by saidpropeller pitch differential operation can produce an essentiallywings-level flat turn of said airplane.